This invention relates to method and apparatus for improving the operation of internal combustion engines and of its fuel metering means. The invention applies to the type of engine having carburetors and of reducing the hydrocarbons emissions from the carburetors and engines systems. It also applies to engines using fuel injection. The invention is accomplished by cooling the fuel supplied to or in the carburetor or fuel injector, that is, in general by supplying fuel to the intake manifold at temperatures cooler than heretofore.
In modern automative vehicles, the temperatures in and around the engines have been considerably raised, even in parts which are not directly related to the operation in the combustion chamber. Thus, the low silhouette of modern cars and the packing of more and more equipment into the lower engine compartment, while trying to keep the car size relatively small have resulted in tight containment of the devices within the engine compartment, and this alone has tended to cause the engine and related equipment, such as the carburetor or fuel injector, to get hotter.
In addition, however, the temperature of the intake manifold has been raised in order to get better fuel-air distribution and to obtain improved vaporization of fuel before it enters the combustion chamber. It is important, of course, to have the fuel well vaporized within the combustion chamber, but the accomplishment of that desideratum has caused heat to be conducted from the combustion chamber, through the intake manifold, to the carburetor or fuel injector. In many instances insulating gaskets have been provided to reduce somewhat the amount of heat transmitted from the intake manifold to the carburetor or fuel injector; but these gaskets have not succeeded in preventing the carburetor or fuel injector from getting quite hot. When the engine is fully warm, the heat transmitted to a carburetor is often sufficient to heat the fuel in the carburetor bowl enough for it to boil. When this fuel boils, some of the vapor emitted therefrom passes directly into the atmospheric air from the carburetor, thereby increasing engine emissions of unburned hydrocarbons.
The boiling of the fuel in the carburetor bowl also changes the effective fuel-air ratio at the carburetor, and some of what is supposed to be air is actually nearly saturated with fuel vapor. A similar problem tends to occur with fuel injectors. This change in the fuel-air ratio reduces the engine efficiency and results in further unburned hydrocarbons entering the atmosphere, in this case from the engine exhaust. The effects of changing the fuel-air ratio in the carburetor or fuel injector in this manner are quite serious, yet under present conditions there is no way of preventing this erratic behavior, since when the fuel does boil within the carburetor or vaporize in the fuel injector, it can no longer be controlled as a liquid.
Thus, the pollution of the air and the economy of operation of the car have both been seriously affected.
In research done on combustion control systems in which additional heat has been added within the combustion system, along with turbulence and water to get better combustion control, I have discovered that operation is affected greatly by the high heat in the carburetor or fuel injector; it became extremely difficult to adjust the carburetor or fuel injector in a manner that would obtain repeatable results. Sometimes the carburetor was almost unmanageable, in the sense of one's being able to maintain a set fuel-air ratio and of being able to keep the engine operating properly, because of this excess heat.
Thus, I have found that the heat needed in the intake manifold in order to vaporize the fuel is not needed in the carburetor or fuel injector and affects performance adversely. In the intake manifold, the vaporization of the fuel enables a good, equal distribution between the cylinders of the supply of fuel and air at the proper ratio, but this ratio is adversely affected when the fuel in the carburetor or fuel injector has been heated too high so that some of the fuel enters as a liquid and some variable proportion enters as a vapor.
I have found that application of the present invention in which the fuel is cooled before it enters the intake manifold enables substantial increase in the effectiveness of the carburetor, and, as a result, in the operation of the engine. Also, the invention reduces the emissions both from the carburetor and from the engine exhaust, since the hydrocarbons supplied can be used consistently and since hydrocarbons are not passed from the carburetor into the air in substantial amounts.